1. Field of the Invention
This invention relates generally to devices adapted for use with micro-computers, and more particularly, to an improved audio power amplification device adapted for use in a micro-computer.
2. Description of Related Art
Micro-computers, such as personal computers are well known in the art. As the use of personal computers in the home and workplace continues to increase at a substantial rate, the demands on these computing devices continues to increase. Personal computers sold today process data faster and have greater data storage capability, than computers sold just a few years ago. As personal computers become more commonplace, the different uses of these computers continues to broaden.
In the past, interaction with a personal computer typically comprised data processing using a keyboard or mouse for data input and a cathode ray tube, commonly referred to as a monitor, or printer for output. However, many of the personal computers in use today embody so-called "multi-media" equipment, which is provided to enhance running programs commonly referred to as "interactive", such as video game programs, and graphical and audible oriented programs. Also, there exists a tendency to extend the use of audio input, such as using a microphone to capture voice commands and intelligence to substitute for keyboard or mouse input.
The so-called multi-media equipment typically includes, a compact disc-read only memory (CD-ROM) drive, digital video disc (DVD) drive, or other similar device coupled to the computer's central processing unit (CPU) using well known means. A printed circuit board having audio signal generating circuitry, typically referred to as a "sound card", is coupled to the CD-ROM drive or DVD and to the CPU using known circuitry and connections. The CPU receives audio related data, processes the data, then transmits the processed data to the audio circuitry. The audio circuitry then generates a line-level audio signal, indicative of the processed data.
The computer utilizes the interaction of these multi-media components to output enhanced video information, such as so-called "full-motion" video displayed on the monitor, and audio information, such as stereophonic sound. However, the actual audio information that the user hears greatly depends upon the type and quality of the audio equipment that receives the audio signal from the audio circuitry.
Since the audio circuitry produces a line-level audio signal, it is known to couple an external loudspeaker or loudspeakers directly to this circuitry to provide enhanced listening of the audio portion of a program running on the computer. Because the signal produced by the audio circuitry is usually line-level, it is desirable to couple a power amplifier between the loudspeaker and the circuitry to increase the power level to sufficiently drive the speaker.
A known embodiment of a loudspeaker that couples to audio circuitry is provided with a low-power audio amplifier. These speakers are provided with a low wattage, from one to two watts, battery powered amplifier and have a somewhat small diameter, of approximately three inches. These loudspeakers have been produced to provide supplemental amplification for portable audio devices such as portable cassette players and radios, and the like. A disadvantage of these loudspeakers, is that since they were initially designed for use in close proximity to the listener's ear, when positioned a distance from the listener the quality of the sound produced by the speakers degrades rapidly.
There are other loudspeakers available that are more suitable for use with audio circuitry than those that embody battery powered amplifiers. However, these loudspeakers are typically cost prohibitive and usually require an external alternating current (AC) power source, such as 120V AC, as is commonly found in the home or office. Another feature of these speakers is that the tone and volume controls are typically coupled to the speaker's enclosure. This is disadvantageous if it is desired to adjust either of the controls and the loudspeakers are out of the listener's reach. The listener would have to momentarily cease their operation of the computer, go to the location of the loudspeakers and adjust the desired control or controls, then return to the computer and resume their task.
Another known attempt to enhance the audio signal generated by programs running on the personal computer comprises positioning a device that embodies both a pair of loudspeakers and an amplifier, in a vacant 5.25 inch drive bay in the computer. One such device is manufactured by Sound Minds Technology, Inc., of Campbell, Calif. The disclosed device embodies a pair of speakers that are coupled to an amplifier. The device couples to an audio information source in the personal computer, with the amplifier of the device coupling to the internal power supply of the computer, for powering the speakers. A disadvantage of the disclosed device is, that since the speakers are retained in the device and the device is housed in the 5.25 inch drive bay, the speakers are in substantially close proximity to each other. Thus, the channel separation normally associated with stereophonic sound is almost nonexistent. Another disadvantage of the device, is that the speakers are substantially small so that they fit in the device. As can be expected, the sound quality produced by the diminutive speakers is somewhat poor.
A further attempt to provide suitable means for enhancing the audio signal generated by the audio circuitry comprises positioning a pair of loudspeakers in the main case of the computer. Various computer manufacturers have positioned a pair of loudspeakers adjacent to a front panel of the computer's case, one speaker positioned at either end of the front panel. In this embodiment, the loudspeaker's amplifier is coupled to the internal power supply of the computer. A disadvantage of this attempt, is that due to the various configurations of computer cases, the speakers may not be in suitable proximity to the listener. A further disadvantage is that while the distance between the loudspeaker provides increased stereo channel separation, the sound produced by the loudspeakers is poor due to small enclosures and inadequate acoustic conditions.
Lastly, another known attempt to enhance the audio signal output from personal computers, is to couple a well known audio power amplifier to the audio circuitry. The amplifier couples to an external AC power source, as discussed above, to the audio circuitry for increasing the power level of the audio signal from the circuitry, and to conventional high fidelity loudspeakers. However, this is substantially difficult to implement, as connecting the amplifier to the audio circuitry requires providing several interconnecting cables between the amplifier and circuitry.
There, therefore exists a need for a facile means of amplifying the audio signal power level from audio signal generating circuitry in a micro-computer, and for enhancing the quality of sound heard by a user, and which can be retained in a drive bay of the micro-computer and further to provide a convenient means to capture voice input.